This is the eighteenth book in a series of near-future Hard-SciFi Thrillers.

Their heroine Ell Donsaii has a nerve mutation that’s rendered her a genius as well as providing her astonishing athletic abilities. Her genius has let her revolutionize our world with a number of inventions, including instantaneous communications and trans-dimensional portals that deliver fuel, water, food, and energy all around the solar system

Invasion is about Russia’s invasion of Georgia, a country that also borders Russia but is much smaller than Ukraine. The President has been advised to call on Ell (who still owes some time on her original Air Force commitment) for ideas. He and his cabinet want to know whether she can think of a way to stop that invasion, but do it without involving the US military—and the possibility of nuclear escalation.

Ell wants to block the invasion and do it with less bloodshed—which plays into the president’s request that she help stop the invasion without directly giving the Georgians any US weaponry.

Her solution is to support the Georgians with “engineering” equipment, rather than any warfighting apparatus.

“Civil engineering equipment” doesn’t sound warlike but it’s good at blocking roads and changing the flow of water, and …

Meanwhile Ell’s twins, Caii and Raii, are incorporating into the family and Ell’s getting D5R back on track after it spent years on the back burner while Ell was finding her lost twin daughters.